feat: gate provider implementation (#611)

## Description



Adds gate.io as a provider to support [umee/usdt](https://www.gate.io/trade/UMEE_USDT)

closes: #604

----

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added appropriate labels to the PR
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/umee-network/umee/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

price-feeder/config/config.go

@@ -23,6 +23,7 @@ const (
 	ProviderOsmosis = "osmosis"
 	ProviderHuobi   = "huobi"
 	ProviderOkx     = "okx"
+	ProviderGate    = "gate"
 	ProviderMock    = "mock"
 )
 
@@ -40,6 +41,7 @@ var (
 		ProviderOsmosis: {},
 		ProviderOkx:     {},
 		ProviderHuobi:   {},
+		ProviderGate:    {},
 		ProviderMock:    {},
 	}
 )
@@ -197,5 +199,15 @@ func ParseConfig(configPath string) (Config, error) {
 		}
 	}
 
+	gatePairs := []string{}
+	for base, providers := range pairs {
+		if _, ok := providers["gate"]; ok {
+			gatePairs = append(gatePairs, base)
+		}
+	}
+	if len(gatePairs) > 1 {
+		return cfg, fmt.Errorf("gate provider does not support multiple pairs: %v", gatePairs)
+	}
+
 	return cfg, cfg.Validate()
 }

price-feeder/oracle/oracle.go

@@ -351,6 +351,13 @@ func (o *Oracle) getOrSetProvider(ctx context.Context, providerName string) (pro
 			}
 			priceProvider = okxProvider
 
+		case config.ProviderGate:
+			gateProvider, err := provider.NewGateProvider(ctx, o.logger, o.providerPairs[config.ProviderGate]...)
+			if err != nil {
+				return nil, err
+			}
+			priceProvider = gateProvider
+
 		case config.ProviderMock:
 			priceProvider = provider.NewMockProvider()
 		}

price-feeder/oracle/oracle_test.go

@@ -41,6 +41,10 @@ func (m mockProvider) GetCandlePrices(_ ...types.CurrencyPair) (map[string][]pro
 	return candles, nil
 }
 
+func (m mockProvider) SubscribeCurrencyPairs(_ ...types.CurrencyPair) error {
+	return nil
+}
+
 type failingProvider struct {
 	prices map[string]provider.TickerPrice
 }
@@ -53,6 +57,10 @@ func (m failingProvider) GetCandlePrices(_ ...types.CurrencyPair) (map[string][]
 	return nil, fmt.Errorf("unable to get candle prices")
 }
 
+func (m failingProvider) SubscribeCurrencyPairs(_ ...types.CurrencyPair) error {
+	return nil
+}
+
 type OracleTestSuite struct {
 	suite.Suite